Johnson 115 backfiring

T

tlar

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Joined
Jun 16, 2003
Messages
2
I own a 1999 Johnson 115 that I had winterized at the local dealer last year. I was told it had stabilizer added to the fuel as part of being winterized. I've had the boat out four weekends and the engine continues to miss and will not run over 4,000 RPM. Thinking it was the carbs., I drained the carbs and added Sea Foam foam spray to the bowls. Didn't seem to help. Next time I took it out it missed for 10 miles, shut it off and then it ran great for 15 minutes @ 5,200 and then started to miss. Primer bulb seems soft but problem doesn't improve when pumping.
 
Joe Reeves

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: Johnson 115 backfiring

Tlar.... If you have proper compression and spark (100+ psi and spark jumps 7/16"), the usual cause is clogged carbs. In which case, the cure is to remove, clean, and rebuild them.
 
T

tlar

Recruit
Joined
Jun 16, 2003
Messages
2
Re: Johnson 115 backfiring

I've checked the compression, power pack and checked spark. All OK. Would problems in the carbs allow it to run great for certain lenghts of time and then start to miss again? I've also had it on the water and pulled individual spark plugs one at a time and the miss never seems to be isolated to a certain cylinder. Could the problem be in the fuel pump and the fuel/oil mixture it is creating. The motor seems to put out more of an oil smell than I remember last year. Could be my imagination though.
 
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